Every professional athlete’s ultimate goal each season is to bring home the championship. Some players work tirelessly every year of their career but are never able to raise a trophy. Others, meanwhile, are able to rise above the competition and win multiple championships over the course of their career.

Since the turn of the century, sports fans have been lucky enough to witness several great dynasties. Players like Sidney Crosby, LeBron James, and Tom Brady have taken their team to the top of their sport again and again. Others, like Tiger Woods, Serena Williams, and Jimmie Johnson, have established their place as some of the most dominant individual athletes of all time.

24/7 Wall St. reviewed championship winners, using the Sports Reference family of sites and other sports databases, to determine the most successful athletes of the 21st century.

Many of the players on this list began to dominate their sports in the 1990s or even the 1980s and continued their dominance and success into the 2000s. Tim Duncan won his first of five NBA championships in 1999. Tiger Woods burst onto the golf scene in 1997, winning his first Masters Tournament less than a year after turning professional.

Since the year 2000, there have been many changes to the sports world. Massive TV contracts with national channels made it possible for sports fans, coast to coast and across the world, to catch more sporting events than ever before. The reach of sports became even greater with the advent of online streaming. Now, practically any sport can be viewed from any part of the globe. This increased exposure both raised the scrutiny on athletes and allowed their triumphs to reach a wider audience.

Many sports fans believe that championships are the ultimate measure of excellence in athletics. To these people, and anyone who retires without a ring can never be considered truly great. Dan Marino was one of the most prolific quarterbacks in NFL history, putting up record breaking statistics. But he never won a Super Bowl and his legacy suffers for it. LeBron James and Michael Jordan are compared ad nauseum, and many fans give Jordan the edge because of his six championships to James’ three.

In order to determine the most successful athletes of the 21st century, 24/7 Wall St. reviewed the careers of top athletes from popular sports across the world. Athletes in team sports were only considered if they won multiple championships since the year 2000. Athletes in individual sports were considered if they won multiple major championships, either as a professional or an Olympian.

Click here to see the 37 most successful athletes of the 21st century.